Asked by harshal duddalwar | 26th Sep, 2010, 12:00: AM

Expert Answer:

Dear student

DC or direct current is produced by DC generators and by batteries also.

Batteries undergo electrochemical reactions to produce direct current.

Electric DC generators are based on the principle of electromagnetic induction. When a conducting loop is moved in a magnetic field, electric current is induced in the loop.

An armature consists of many turns of a coil placed between the poles of a strong magnet.

The ends of the coil are connected to a split-ring commutator R1 and R2. Two carbon brushes B1 and B2 press lightly against the two halves of the commutator

1. Armature ABCD is rotated in anti clockwise direction inside the magnetic field.
2. Applying Fleming's right hand rule to arm AB (moving downwards), (fig a) the direction of the induced current is found to be upwards (along AB).
3. Applying Fleming right hand rule to the arm CD (moving upwards) the direction of the induced current is found to be downwards (along CD)
4. For the half rotation of the armature hence the direction of the induced current in the armature is clockwise i.e. ABCD B2R B1 A.
5. Similarly for the next half rotation of the armature (fig b) applying Fleming's RH rule gives the direction of induced current to be again clockwise i.e, DCBAB2RB1D.
6. Thus during the entire rotation, the current through load resistor R remains the same. The nature of the current produced is hence dc (direct current).
We hope that clarifies your query.

Answered by  | 28th Sep, 2010, 09:58: AM

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